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  • Author or Editor: Ella Reeves x
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Grafted tomato (Solanum lycopersicum L.) plants have the potential to increase yield in the absence of soilborne disease; however, success is dependent on geographic location and rootstock–scion combination. Pruning axillary shoots on field-grown tomato plants is a standard practice for fresh-market production in the southeastern United States, although few studies have evaluated the effects of pruning grafted tomato plants. In this study, we evaluated six field grown tomato rootstock–scion combinations and their nongrafted counterparts, pruned or not pruned, over the course of 2 years at one location in North Carolina. Total yield, fruit size, variable cost of inputs, and net return data were analyzed. In both years of the study, cultivars Mountain Gem and Jolene had high yield of jumbo and extra-large fruit when grafted onto ‘Maxifort’ or ‘Beaufort’ rootstock. Yield was higher (P < 0.0001) for plants that were grafted and not pruned compared with nongrafted pruned plants (grower standard). Net return from the treatment where plants were grafted onto ‘Maxifort’ rootstock and not pruned was greater than that from the grower standard practice, although this was not the case in both years of the study. The variable cost of growing grafted plants that were not pruned was always greater than that of the grower standard practice due to the greater cost of transplants and labor associated with harvest. The results from this study emphasize the importance of evaluating a small number of prospective rootstock–scion combinations on-farm and considering the balance between higher input costs of the grafted plants and potential increased yields before planting an entire field.

Open Access

Phytophthora crown and root rot, caused by the oomycete pathogen Phytophthora capsici, is a devastating disease of squash and pumpkin (Cucurbita pepo). No currently available cultivars provide complete resistance to this disease. Three newly developed squash lines and four hybrids were evaluated in greenhouse and field experiments for their resistance to phytophthora crown and root rot as well as for their horticultural performance. The three newly developed lines ranked among the most resistant entries included in 2 years of field trials. In addition, in a separate greenhouse experiment, one of the lines was shown to display the least severe disease symptoms among a group of accessions previously reported to possess partial resistance to phytophthora crown and root. Furthermore, the resistance was observed to be robust to several isolates of P. capsici. However, the phytophthora-resistant lines had reduced yield relative to standard squash cultivars. These lines are useful for continued breeding efforts toward a phytophthora crown and root rot-resistant cultivar.

Open Access

Host resistance is an environmentally and economically sustainable disease management strategy that may be especially beneficial to small-scale and organic growers for whom other management tools such as synthetic pesticides are too costly or not permitted. In western North Carolina, the demand for vine-ripened tomatoes (Solanum lycopersicum L.) from local and organic farms has led to the development of cultivars bred for resistance to geographically relevant diseases, including late blight of tomato, which causes rapid defoliation and lesions on fruit. Grafting tomato plants has the potential to increase plant vigor and yield; however, this effect is known to be dependent on multiple factors, including scion and geographic location. In this study, we evaluated the yield response of one determinate (‘Mountain Gem’) and four indeterminate (‘Mountain Heritage’, ‘Mountain Girl’, ‘Mountain Rouge’, and ‘NC10291’) late blight–resistant tomato cultivars, grafted on tomato rootstock ‘Maxifort’ or nongrafted, on a commercial farm and at two research facilities in western North Carolina. Yield of marketable fruit from grafted plants was greater than that from nongrafted plants at one location (P = 0.008); however, yield response of each cultivar, grafted or not grafted, differed by location. Yield was consistently greater from ‘Mountain Gem’ plants than other cultivars, and grafted ‘Mountain Gem’ plants had greater yields later in the season at two locations than nongrafted plants. Because of the late planting date intended to expose cultivars to the late blight pathogen, the full yield potential of the indeterminate cultivars was not realized at all locations. Disease severity caused by Verticillium wilt (Verticillium dahliae Kleb., Verticillium albo-atrum Reinke & Berthold) was lowest for cultivar Mountain Heritage at two of three locations. Results from this study emphasize the importance of conducting evaluations of grafted tomato plants at multiple locations, including on farm, to optimize the benefits associated with their use.

Open Access